CN111564144B - Power supply switching control circuit and display device - Google Patents
Power supply switching control circuit and display device Download PDFInfo
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- CN111564144B CN111564144B CN202010371301.0A CN202010371301A CN111564144B CN 111564144 B CN111564144 B CN 111564144B CN 202010371301 A CN202010371301 A CN 202010371301A CN 111564144 B CN111564144 B CN 111564144B
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
- G09G3/3406—Control of illumination source
Abstract
The invention provides a power supply switching control circuit and a display device, wherein the power supply switching control circuit comprises a voltage input end electrically connected with a power supply module, a voltage output end electrically connected with a backlight lamp, a control signal input end, a voltage stabilizing switch circuit, a power supply switch circuit and a current amplifying circuit; the controlled end of the voltage stabilizing switch circuit is connected with the control signal input end, the first connecting end of the voltage stabilizing switch circuit is connected with the controlled end of the power switch circuit, and the second connecting end of the voltage stabilizing switch circuit is grounded; the controlled end of the current amplifying circuit is connected with the voltage input end, the input end of the current amplifying circuit is connected with the voltage input end, and the output end of the current amplifying circuit is connected with the controlled end of the power switch circuit; the input end of the power switch circuit is connected with the voltage input end, and the output end of the power switch circuit is connected with the voltage output end. The technical scheme of the invention can solve the problem that the power supply switching control device is slow to switch when the scanning type driving backlight lamp is adopted.
Description
Technical Field
The invention relates to the technical field of display, in particular to a power supply switching control circuit and a display device.
Background
Mini LEDs (also known as millimeter light emitting diodes) are of great industrial interest as a new technology with a wide market prospect. The Mini LED backlight has the characteristics of lightness, thinness, high image quality, low power consumption and the like. In addition, the Mini LED backlight can be combined with a fine area division technology to control the on-off and the brightness of the corresponding backlight area in real time according to the brightness of each position of the picture in the television signal, so that the black display area in the picture is darker, high contrast is presented, and the color is more gorgeous.
The Mini LED is usually supplied with high voltage and is driven by a scanning backlight driving method. The Mini LED is driven by adopting a scanning type backlight driving method, and the opening time of adjacent scanning lines cannot be crossed technically so as to avoid influencing the display effect of a television. However, the scanning backlight driving method is adopted to drive the high-area backlight, and the power supply switching control device has the problems of low switching speed, large circuit loss, low reliability and the like.
Disclosure of Invention
The invention provides a power supply switching control circuit and a display device, and aims to solve the problem that the switching speed of the power supply switching control device is slow when a scanning type driving high-partition backlight lamp is adopted at present.
In order to achieve the above object, the present invention provides a power switching control circuit, which includes a voltage input terminal electrically connected to a power supply module, a voltage output terminal electrically connected to a backlight, a control signal input terminal, a voltage stabilizing switch circuit, a power switch circuit, and a current amplifying circuit;
the controlled end of the voltage stabilizing switch circuit is connected with the control signal input end, the first connecting end of the voltage stabilizing switch circuit is connected with the controlled end of the power switch circuit, and the second connecting end of the voltage stabilizing switch circuit is grounded;
the controlled end of the current amplification circuit is connected with the voltage input end, the input end of the current amplification circuit is connected with the voltage input end, and the output end of the current amplification circuit is connected with the controlled end of the power switch circuit;
the input end of the power switch circuit is connected with the voltage input end, and the output end of the power switch circuit is connected with the voltage output end;
the voltage stabilizing switch circuit is used for triggering the power switch circuit to be conducted when receiving a conducting signal input by the control signal input end;
the voltage stabilizing switch circuit is also used for triggering the power switch circuit to be switched off when receiving a turn-off signal input by the control signal input end;
the current amplifying circuit is used for generating a turn-off driving current to the power switch circuit when the voltage stabilizing switch circuit triggers the power switch circuit to be turned off so as to accelerate the turn-off speed of the power switch circuit.
Optionally, the voltage stabilizing switch circuit includes a first resistor, a second resistor, a first transistor, a diode, a first capacitor, and a voltage stabilizing module;
a first end of the first resistor is connected with the control signal input end, and a second end of the first resistor is connected with a first end of the second resistor, a first end of the first capacitor and a controlled end of the first transistor; a second end of the second resistor, a second end of the first capacitor and a second connecting end of the first transistor are grounded;
the first connection end of the first transistor is connected with the cathode of the diode through the voltage stabilizing module, and the anode of the diode is connected with the controlled end of the power switch circuit.
Optionally, the voltage stabilizing module includes a first voltage stabilizing diode, a second voltage stabilizing diode and a third voltage stabilizing diode;
the anode of the first voltage stabilizing diode is connected with the first connecting end of the first transistor, and the cathode of the first voltage stabilizing diode is connected with the anode of the second voltage stabilizing diode; and the cathode of the second voltage-stabilizing diode is connected with the anode of the third voltage-stabilizing diode, and the cathode of the third voltage-stabilizing diode is connected with the controlled end of the power switch circuit.
Optionally, the first transistor is an N-MOS transistor;
the grid electrode of the N-MOS tube is the controlled end of the first transistor, the drain electrode of the N-MOS tube is the first connecting end of the first transistor, and the source electrode of the N-MOS tube is the second connecting end of the first transistor.
Optionally, the current amplifying circuit includes a fifth resistor and an NPN triode;
a first end of the fifth resistor is connected with the voltage input end, and a second end of the fifth resistor is connected with a base electrode of the NPN triode and a negative electrode of the diode;
and the collector of the NPN triode is connected with the voltage input end, and the emitter of the NPN triode is connected with the controlled end of the power switching circuit.
Optionally, the power switch circuit includes a third resistor, a fourth resistor, and a second transistor;
the first end of the third resistor is a controlled end of the power switch circuit, and the second end of the third resistor is connected with the first end of the fourth resistor and the controlled end of the second transistor;
the first connecting end of the second transistor is the input end of the power switch circuit and is connected with the second end of the fourth resistor; and the second connecting end of the second transistor is the output end of the power switch circuit.
Optionally, the second transistor is a P-MOS transistor;
the grid electrode of the P-MOS transistor is the controlled end of the second transistor, the source electrode of the P-MOS transistor is the first connecting end of the second transistor, and the drain electrode of the P-MOS transistor is the second connecting end of the second transistor.
Optionally, the power switching control circuit further includes a discharging circuit;
the input end of the discharge circuit is connected with the voltage output end, and the output end of the discharge circuit is grounded.
Optionally, the discharge circuit includes a second capacitor, a sixth resistor, a seventh resistor, an eighth resistor, and a ninth resistor;
the first end of the second capacitor, the first end of the sixth resistor, the first end of the seventh resistor, the first end of the eighth resistor and the first end of the ninth resistor are all connected with the voltage output end; the second end of the second capacitor, the second end of the sixth resistor, the second end of the seventh resistor, the second end of the eighth resistor and the second end of the ninth resistor are all grounded.
In order to achieve the above object, the present invention further provides a display device, which includes the power switching control circuit as described above.
According to the technical scheme, when the input end of the control signal inputs a conducting signal, the voltage stabilizing switch circuit is conducted, and the power supply switch circuit is triggered to be rapidly conducted through the conduction of the voltage stabilizing switch circuit, so that the power supply module provides high-voltage electric energy for the backlight lamp; when the input end of the control signal inputs a turn-off signal, the voltage stabilizing switch circuit is switched off, the switching-off of the power switch circuit is triggered by the switching-off of the voltage stabilizing switch circuit, and the switching-off speed of the power switch circuit is accelerated by the current amplifying circuit, so that the switching speed of the power switch circuit and the control signal input by the input end of the control signal tend to be synchronous, the crossing of the opening time of the current scanning line and the opening time of the next scanning line is avoided, and the display device can normally display pictures.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a block diagram of a power switching control circuit according to an embodiment of the present invention;
FIG. 2 is a block diagram of a Mini LED drive architecture in an exemplary embodiment;
FIG. 3 is a schematic circuit diagram of a power switching control circuit according to an embodiment of the present invention;
FIG. 4 is a block diagram of another embodiment of a power switching control circuit according to the present invention;
fig. 5 is a schematic circuit diagram of a power switching control circuit according to another embodiment of the invention.
The reference numbers illustrate:
| 10 | voltage-stabilizing |
20 | |
| 30 | Current amplifying |
40 | |
| 101 | Voltage stabilizing module | Q1 | A first transistor |
| Q2 | Second transistor | Q3 | NPN triode |
| R1～R9 | First to ninth resistors | T1 | First voltage regulator diode |
| T2 | Second voltage regulator diode | T3 | Third voltage regulator diode |
| C1 | First capacitor | C2 | Second capacitor |
| D2 | Diode with a high-voltage source | GND | Ground |
| Vin | Voltage input terminal | Vout | |
| 100 | Power supply |
200 | |
| 300 | Constant current control system |
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that, if directional indications (such as up, down, left, right, front, and back … …) are involved in the embodiment of the present invention, the directional indications are only used to explain the relative positional relationship between the components, the movement situation, and the like in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indications are changed accordingly.
In addition, if there is a description of "first", "second", etc. in an embodiment of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
Fig. 1 is a block diagram of a power switching control circuit according to an embodiment of the invention.
Referring to fig. 1, the power switching control circuit includes a voltage input terminal Vin electrically connected to the power supply module, a voltage output terminal Vout electrically connected to a backlight on a scan line, a control signal input terminal EN, a voltage stabilizing switch circuit 10, a power switch circuit 20, and a current amplifying circuit 30;
the controlled end of the voltage stabilizing switch circuit 10 is connected with the control signal input end EN, the first connection end of the voltage stabilizing switch circuit 10 is connected with the controlled end of the power switch circuit 20, and the second connection end of the voltage stabilizing switch circuit 10 is grounded; the controlled end of the current amplifying circuit 30 is connected to the voltage input end Vin, the input end of the current amplifying circuit 30 is connected to the voltage input end Vin, and the output end of the current amplifying circuit 30 is connected to the controlled end of the power switch circuit 20. The input terminal of the power switch circuit 20 is connected to the voltage input terminal Vin, and the output terminal of the power switch circuit 20 is connected to the voltage output terminal Vout.
The voltage stabilizing switch circuit 10 has two states of on and off, and when the voltage stabilizing switch circuit 10 is turned on, the voltage stabilizing switch circuit can trigger the power switch circuit 20 to be turned on, and clamp the potential of the controlled end of the power switch circuit 20 at a certain fixed voltage. When the voltage stabilizing switch circuit 10 is turned off, the power switch circuit 20 can be triggered to turn off.
The current amplifying circuit 30 may be implemented by a circuit composed of a triode element or other circuits with current amplifying function. The current amplifying circuit 30 is configured to provide a sufficient off-driving current to the controlled terminal of the power switch circuit 20 when the power switch circuit 20 is triggered to turn off, so as to accelerate the turn-off speed of the power switch circuit 20.
The power switch circuit 20 has two states of on and off, and can be implemented by a circuit composed of MOS transistors.
The technical solution of this embodiment can be applied to a display device using a Mini LED as a backlight, for example, a television using a Mini LED as a backlight. At present, a display device using a Mini LED as a backlight source usually uses high voltage to supply power to the Mini LED, and drives the high-partition Mini LED in a scanning manner. For example, a Mini LED driving architecture shown in fig. 2 includes a power switching control device 100, a Mini LED module 200, and a constant current control system 300. The driving structure is set to drive the high-partition Mini LED by adopting a 5-scan scanning mode, the scanning frequency is F (1KHz to 10KHz), the switching period of the power supply switching control device 100 is T, the on time of each scanning line is about T/5 (the line-to-line middle also includes a very short dead time), and the scanning line 1, the scanning line 2, the scanning line 3, the scanning line 4 and the scanning line 5 are sequentially and alternately conducted at a duty ratio of about 20%. Therefore, in order to make the display device normally display, the on-time of the previous scan line cannot cross the on-time of the next scan line, and therefore, the switching speed of each switching tube in the power supply switching control device 100 needs to be fast enough.
In order to solve the above problems, the present invention provides a power switching control circuit, which is applied to a power switching control device. The power switching control device includes a plurality of power switching control circuits with the same structure, and each power switching control circuit is used for controlling the switch of one scanning line.
Specifically, when the control signal input terminal EN inputs a turn-on signal to the voltage stabilizing switch circuit 10, the voltage stabilizing switch circuit 10 can be triggered to turn on. The conducting signal may be a high level or a low level, and may be specifically set according to the type of the transistor in the voltage stabilizing switch circuit 10, the control signal may be sent by a controller of the system, and the controller in the system controls the operation of the entire Mini LED backlight system, and is responsible for communication with a main SOC (system on chip) and a backlight control chip and power supply control of a scan line. When the voltage stabilizing switch circuit 10 is turned on, the power switch circuit 20 can be triggered to be turned on, and the controlled end of the power switch circuit 20 is clamped at a certain fixed voltage. If the resistance value of the driving resistor of the MOS transistor in the power switch circuit 20 is set to be small enough, for example, 2 ohms, 2.2 ohms, etc., then when the voltage stabilizing switch circuit 10 is turned on, the on-state driving current of the MOS transistor in the power switch circuit 20 is large enough, so that when the voltage stabilizing switch circuit 10 is turned on, the power switch circuit 20 can be triggered to be turned on quickly, so that the voltage input terminal Vin and the voltage output terminal Out are electrically connected quickly, and the power supply module outputs high-voltage electric energy, for example, 46V high-voltage electric energy to supply power to the backlight lamp of the scanning line where the power switch control circuit is located.
When the control signal input end EN inputs a turn-off signal to the voltage stabilizing switch circuit 10, the voltage stabilizing switch circuit 10 can be controlled to be turned off, the power switch circuit 20 is triggered to be turned off by controlling the voltage stabilizing switch circuit 10 to be turned off, and the current amplifying circuit is triggered to be turned on. In the process of turning off the power switch circuit 20, the current amplifier circuit 30 provides a sufficient turn-off driving current for the power switch circuit 20 to increase the turn-off speed of the power switch circuit 20, and the power supply module stops supplying power to the backlight lamp of the scanning line where the power switch control circuit is located. That is to say, in the technical solution of this embodiment, the voltage stabilizing switch circuit 10 is combined with the current amplifying circuit 20 to increase the switching speed of the power switch circuit 20, so that the switching speed of the power switch circuit 20 tends to be synchronous with the control signal input by the control signal input terminal EN, thereby avoiding the crossing of the on-time of the current scan line and the next scan line, and ensuring that the display device can normally display the image.
According to the technical scheme, when a control signal input end EN inputs a conducting signal, the voltage stabilizing switch circuit 10 is conducted, and the power switch circuit 20 is triggered to be rapidly conducted through the conduction of the voltage stabilizing switch circuit 10, so that a power supply module supplies power to a backlight lamp of a scanning line where the power switching control circuit is located; when the control signal input end EN inputs a turn-off signal, the voltage stabilizing switch circuit 10 is turned off, the power switch circuit 20 is triggered to be turned off by turning off the voltage stabilizing switch circuit 10, and the turn-off speed of the power switch circuit 20 is increased by the current amplifying circuit 30, so that the switching speed of the power switch circuit 20 and the control signal input by the control signal input end EN tend to be synchronous, the turn-on time crossing of the current scanning line and the next scanning line is avoided, and the display device can normally display the picture.
Optionally, referring to fig. 3, in an embodiment, the voltage stabilizing switching circuit 10 includes a first resistor R1, a second resistor R2, a first transistor Q1, a diode D1, a first capacitor C1, and a voltage stabilizing module 101;
a first end of the first resistor R1 is connected to the control signal input terminal EN, and a second end of the first resistor R1 is connected to a first end of the second resistor R2, a first end of the first capacitor C1, and a controlled end of the first transistor Q1; the second end of the second resistor R2, the second end of the first capacitor C1 and the second connection terminal of the first transistor Q1 are grounded; the first connection terminal of the first transistor Q1 is connected to the cathode of the diode D1 through the voltage regulator 101, and the anode of the diode D1 is connected to the controlled terminal of the power switch circuit 20.
In this embodiment, the first transistor Q1 may be a P-MOS transistor or an N-MOS transistor. For convenience of explanation, the operation principle of the voltage regulator switching circuit 10 will be described below by taking the first transistor Q1 as an N-MOS transistor as an example. The gate of the N-MOS transistor is set as the controlled terminal of the first transistor Q1, the drain of the N-MOS transistor is the first connection terminal of the first transistor Q1, and the source of the N-MOS transistor is the second connection terminal of the first transistor Q1. It should be noted that, since the MOS transistor is a voltage control device, its operating state is mainly determined by the gate-source voltage Vgs, that is, when Vgs is smaller than the turn-on voltage of the MOS transistor, the MOS transistor operates in the off state, and when Vgs is greater than the turn-on voltage of the MOS transistor, the MOS transistor operates in the on state. A parasitic capacitor exists between the grid electrode and the drain electrode of the MOS tube, and the driving of the MOS tube actually charges and discharges the capacitor. Therefore, when the N-MOS tube is selected, the selected Vds voltage is high enough, and the junction capacitance between the grid electrode and the source electrode of the MOS tube and the grid electrode and the drain electrode of the MOS tube is small enough, so that the switching speed of the MOS tube and the control signal tend to be synchronous.
Specifically, when the control signal input terminal EN inputs a high-level conduction signal, the N-MOS transistor Q1 is turned on, and at this time, the voltage regulation module 101 clamps the cathode of the diode D1 at a certain fixed voltage, for example, at 42V, and due to the voltage drop effect of the diode D1, the anode voltage of the diode D1 is greater than the cathode voltage thereof, for example, the anode voltage of the diode D1 is clamped at about 42.7V. If the resistance value of the driving resistor on the gate of the MOS transistor in the power switch circuit 20 is set to be small enough, for example, 2 ohms, 2.2 ohms, etc., then when the N-MOS transistor Q1 is turned on, the on driving current of the MOS transistor in the power switch circuit 20 is large enough, so that when the N-MOS transistor Q1 is turned on, the power switch circuit 20 can be triggered to be turned on quickly, the voltage input terminal Vin and the voltage output terminal Out are electrically connected quickly, and the power supply module outputs high-voltage power, for example, 46V high-voltage power to supply power to the backlight of the scanning line where the power switch control circuit is located. By such an arrangement, the on speed of the power switch circuit 20 and the on signal input by the control signal input end EN tend to be synchronous. Meanwhile, the gate of the MOS transistor in the power switch circuit 20 discharges through the driving resistor of the power switch circuit 20, the diode D1, the voltage regulator block 101, and the N-MOS transistor Q1. Because the power consumption of the voltage stabilizing module 101 is smaller, the circuit loss can be reduced, and the over-high temperature of the circuit can be avoided. The voltage stabilizing module 101 determines a voltage fluctuation range of the MOS transistor in the power switch circuit 20, for example, controls a voltage of a controlled terminal of the MOS transistor in the power switch circuit 20 to be between 42V and 46V, further increases a conduction speed of the MOS transistor in the power switch circuit 20, and simultaneously prevents the MOS transistor in the power switch circuit 20 from being burned out.
Optionally, in an embodiment, the voltage regulation module 101 includes a first voltage regulation diode T1, a second voltage regulation diode T2, and a third voltage regulation diode T3; the anode of the first zener diode T1 is connected to the first connection terminal of the first transistor Q1, and the cathode of the first zener diode T1 is connected to the anode of the second zener diode T2; the cathode of the second zener diode T2 is connected to the anode of the third zener diode T3, and the cathode of the third zener diode T3 is connected to the controlled terminal of the power switch circuit 20. Optionally, the first zener diode T1, the second zener diode T2, and the third zener diode T3 may be implemented by zener diodes with the same specification, for example, zener diodes with a zener voltage value of 14V, or may be implemented according to the voltage withstanding value of the MOS transistor in the power switch circuit 20, which is not limited herein.
Optionally, referring to fig. 3, in an embodiment, the current amplifying circuit 30 includes a fifth resistor R5 and an NPN triode Q3; a first end of the fifth resistor R5 is connected to the voltage input terminal Vin, and a second end of the fifth resistor R5 is connected to the base of the NPN transistor Q3 and the negative electrode of the diode D1 in the voltage regulator circuit 10; the collector of the NPN transistor Q3 is connected to the voltage input terminal Vin, and the emitter of the NPN transistor Q3 is connected to the controlled terminal of the power switch circuit 20.
The specific working principle is as follows: when the voltage regulator circuit 10 is on, the NPN transistor Q3 is in an off state. When the voltage stabilizing switch circuit 10 is turned off, the NPN transistor Q3 is turned on by the driving action of the fifth resistor R5. Since the NPN transistor Q3 has a current amplification function, when the voltage regulator circuit 10 is turned off, the NPN transistor Q3 can provide a sufficiently large off driving current for the gate of the MOS transistor in the power switch circuit 20, for example, the base current of the NPN transistor Q3 is set to Ib, so that the off driving current for the gate of the MOS transistor in the power switch circuit 20 can reach β × Ib, so that when the voltage regulator circuit 10 is turned off, the gate voltage of the MOS transistor in the power switch circuit 20 becomes high, for example, equal to the voltage input by the voltage input terminal Vin, so that the MOS transistor in the power switch circuit 20 is turned off quickly, and thus, the turn-off speed of the power switch circuit 20 and the turn-off signal input by the control signal input terminal EN can be synchronized. The diode D1 in the voltage stabilizing switch circuit 10 is used to protect the base of the NPN transistor Q3, so as to avoid the NPN transistor Q3 from being damaged due to the fact that the voltage difference between the emitter voltage and the base voltage of the NPN transistor Q3 exceeds a limit value. This fifth resistance R5 is the current-limiting resistor, and when the steady voltage switch circuit 10 switched on, because the current-limiting effect of fifth resistance R5 can make the consumption of steady voltage module 101 in the steady voltage switch circuit 10 less to effectively reduce the circuit loss, avoid the circuit high temperature.
Optionally, referring to fig. 3, in an embodiment, the power switch circuit 20 includes a third resistor R3, a fourth resistor R4, and a second transistor Q2; a first terminal of the third resistor R3 is a controlled terminal of the power switch circuit 20, and a second terminal of the third resistor R3 is connected to a first terminal of the fourth resistor R4 and a controlled terminal of the second transistor Q2; the first connection terminal of the second transistor Q2 is the input terminal of the power switch circuit 20 and is connected to the second terminal of the fourth resistor R4; the second connection terminal of the second transistor Q2 is the output terminal of the power switch circuit 20.
The second transistor Q2 can be a P-MOS transistor, the gate of the P-MOS transistor is the controlled terminal of the second transistor Q2, the source of the P-MOS transistor is the first connection terminal of the second transistor Q2, and the drain of the P-MOS transistor is the second connection terminal of the second transistor Q2. It should be noted that, since the MOS transistor is a voltage control element, its operating state is mainly determined by the gate-source voltage Vgs, that is, when Vgs is smaller than the turn-on voltage, the MOS transistor operates in the off state, and when Vgs is greater than the turn-on voltage, the MOS transistor operates in the on state. A parasitic capacitor exists between the grid electrode and the drain electrode of the MOS tube, and the driving of the MOS tube actually charges and discharges the capacitor. Therefore, when the P-MOS transistor Q2 is selected, the selectable Vds voltage is high enough, the junction capacitance between the gate and the source of the MOS transistor and between the gate and the drain of the MOS transistor is small enough, so as to further ensure that the switching speed of the P-MOS transistor is close to the control signal.
Specifically, when the regulator switch circuit 10 is turned on, the gate of the P-MOS transistor Q2 is clamped at a certain fixed voltage, for example, at about 42.7V, and at this time, the P-MOS transistor Q2 is turned on. If the resistance of the third resistor R3 is set to be small enough, for example, 2 ohms or 2.2 ohms, then the on-driving current of the gate of the P-MOS transistor Q2 can be made large enough, and the P-MOS transistor Q2 can be turned on quickly. That is, the third resistor R3 of the gate of the P-MOS transistor Q2 is set to be a resistor with a small resistance value, so that when the voltage stabilizing switch circuit 10 is turned on, the on driving current of the gate of the P-MOS transistor Q2 is large enough, and the on of the P-MOS transistor Q2 and the on signal input by the control signal input end EN tend to be synchronous. The fast conduction of the P-MOS transistor Q2 can make the voltage input terminal Vin and the voltage output terminal Out be electrically connected fast, and the power supply module outputs high-voltage power, for example, 46V of high-voltage power to supply power to the backlight on the scanning line where the power switching control circuit is located.
When the regulator switch circuit 10 is turned off, the current amplification circuit 30 is turned on by its internal drive resistor. Since the current amplifying circuit 30 has a current amplifying function, when the voltage stabilizing switch circuit 10 is turned off, the current amplifying circuit 30 can provide a sufficient off-drive current for the gate of the P-MOS transistor Q2, so that the gate voltage of the P-MOS transistor Q2 rapidly increases, for example, equal to the voltage input by the voltage input terminal Vin, thereby triggering the P-MOS transistor Q2 to rapidly turn off, and causing the turn-off speed of the P-MOS transistor Q2 to be synchronous with the turn-off signal input by the control signal input terminal.
Optionally, referring to fig. 4, in an embodiment, the power switching control circuit further includes a discharging circuit 40; the input terminal of the discharge circuit 40 is connected to the voltage output terminal Vout, and the output terminal of the discharge circuit 40 is grounded.
The discharging circuit 40 is used for rapidly discharging the residual charges of the back-end circuit when the power switch circuit 20 is turned off, so that the voltage of the voltage output end Vout is rapidly lowered, and further, the crossing of the on-time of the adjacent scanning lines is avoided, thereby effectively improving the stability and reliability of the display device.
Optionally, referring to fig. 5, in an embodiment, the discharge circuit 40 includes a second capacitor C2, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, and a ninth resistor R9; the first end of the second capacitor C2, the first end of the sixth resistor R6, the first end of the seventh resistor R7, the first end of the eighth resistor R8 and the first end of the ninth resistor R9 are all connected to the voltage output terminal Vout; the second terminal of the second capacitor C2, the second terminal of the sixth resistor R6, the second terminal of the seventh resistor R7, the second terminal of the eighth resistor R8, and the second terminal of the ninth resistor R9 are all grounded.
In this embodiment, when the power switch circuit 20 is turned off, the residual charges of the back-end circuit are discharged at a high speed through the sixth resistor R6, the seventh resistor R7, the eighth resistor R8 and the ninth resistor R9, so that the voltage of the voltage output terminal Vout is rapidly lowered, and the crossing of the on-times of adjacent scan lines is further avoided, thereby effectively improving the stability and reliability of the display device.
To better illustrate the inventive concepts of the present invention, the overall inventive concepts of the present invention are described below in conjunction with FIG. 5.
Referring to fig. 5, when the control signal input from the control signal input terminal EN is at a high level, the N-MOS transistor Q1 is turned on. The first zener diode T1, the second zener diode T2 and the third zener diode T3 clamp the cathode of the diode D1 at a certain fixed voltage, for example, at 42V, and since the diode D1 has a certain voltage drop effect, the anode voltage of the diode D1 is greater than the cathode voltage thereof, for example, when the cathode voltage of the diode D1 is 42V, the anode voltage of the diode D1 is about 42.7V. At this time, due to the current limiting function of the fifth resistor R5, for example, the current limiting function of the fifth resistor R5 of 2.2K Ω, the power consumption generated by the first zener diode T1, the second zener diode T2 and the third zener diode T3 is smaller, the circuit loss can be effectively reduced, and the over-high circuit temperature can be avoided. Meanwhile, since the resistance of the third resistor R3 of the P-MOS transistor Q2 is small, for example, 2.2 Ω, the on-driving current of the P-MOS transistor Q2 is large enough, so that the P-MOS transistor Q2 can be turned on quickly, and the on-speed of the P-MOS transistor Q2 is synchronous with the high-level control signal input by the control signal input terminal EN. At this time, the power supply module outputs high voltage power, for example, 46V of high voltage power to supply power to the backlight of the scan line where the power switching control circuit is located.
When the control signal input by the control signal input terminal EN is at a low level, the N-MOS transistor Q1 is turned off, and the first zener diode T1, the second zener diode T2, and the third zener diode T3 are in an open state. And the NPN transistor Q3 is turned on under the driving action of the fifth resistor R5. Because the NPN triode Q3 has a current amplification function, the amplification factor is often hundreds of times, which can make the turn-off driving current of the P-MOS transistor Q2 large enough to finally trigger the P-MOS transistor Q2 to turn off rapidly, so that the turn-off speed of the P-MOS transistor Q2 and the low-level control signal input by the control signal input end tend to be synchronous. Meanwhile, the residual charges of the back-end circuit are discharged at a high speed through the sixth resistor R6, the seventh resistor R7, the eighth resistor R8 and the ninth resistor R9, so that the voltage of the voltage output end Vout is rapidly lowered, the crossing of the opening time of adjacent scanning lines is further avoided, and the display stability and reliability of the display device are effectively improved. That is to say, the technical scheme of the invention can realize that the control signal input end and the switch of the P-MOS tube tend to be synchronous, thereby avoiding the crossing of the opening time of the current scanning line and the opening time of the next scanning line, ensuring that the display device can normally display the picture and ensuring that the display effect is more stable.
The diode D1 is used to protect the NPN transistor Q3, so as to prevent the NPN transistor Q3 from being damaged due to the fact that the voltage difference between the emitter voltage and the base voltage of the NPN transistor Q3 exceeds a limit value. The first zener diode T1, the second zener diode T2, and the third zener diode T3 are configured to clamp the gate voltage of the P-MOS transistor Q2 in a certain voltage range, for example, between 42V and 46V, which is beneficial to reduce the voltage variation of the P-MOS transistor Q2, accelerate the conduction speed of the P-MOS transistor Q2, and prevent the P-MOS transistor Q2 from being damaged. Meanwhile, the first zener diode T1, the second zener diode T2, and the third zener diode T3 are also used to realize switching control of high voltage to low voltage.
In summary, in the technical solution of the present invention, the current amplifying circuit 30 formed by a triode is combined with the voltage stabilizing switch circuit 20, so as to solve the problem of large loss when the power switch circuit 20 is turned on, and the problem of small off driving current when the power switch circuit 20 is turned off, thereby effectively ensuring that the control signal and the switch of the power switch circuit 20 tend to be synchronous, and ensuring that the display device can normally display the picture.
The invention also provides a display device, which comprises the power supply switching control circuit, wherein the detailed structure of the power supply switching control circuit can refer to the embodiment and is not described again; it can be understood that, since the display device of the present invention uses the power switching control circuit, the embodiment of the display device of the present invention includes all technical solutions of all embodiments of the power switching control circuit, and the achieved technical effects are also completely the same, and are not described herein again.
The above description is only an alternative embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (10)
1. A power supply switching control circuit is characterized by comprising a voltage input end electrically connected with a power supply module, a voltage output end electrically connected with a backlight lamp, a control signal input end, a voltage stabilizing switch circuit, a power supply switch circuit and a current amplifying circuit;
the controlled end of the voltage stabilizing switch circuit is connected with the control signal input end, the first connecting end of the voltage stabilizing switch circuit is connected with the controlled end of the power switch circuit, and the second connecting end of the voltage stabilizing switch circuit is grounded;
the controlled end of the current amplification circuit is connected with the voltage input end, the input end of the current amplification circuit is connected with the voltage input end, and the output end of the current amplification circuit is connected with the controlled end of the power switch circuit;
the input end of the power switch circuit is connected with the voltage input end, and the output end of the power switch circuit is connected with the voltage output end;
the voltage stabilizing switch circuit is used for triggering the power switch circuit to be conducted when receiving a conducting signal input by the control signal input end, and positioning a potential clamp at a controlled end of the power switch circuit at a fixed voltage;
the voltage stabilizing switch circuit is also used for triggering the power switch circuit to be switched off when receiving a turn-off signal input by the control signal input end;
the current amplifying circuit is used for generating a turn-off driving current to the power switch circuit when the voltage stabilizing switch circuit triggers the power switch circuit to be turned off so as to accelerate the turn-off speed of the power switch circuit, so that the switching speed of the power switch circuit is approximately synchronous with a control signal input by the control signal input end, the crossing of the turn-on time of the current scanning line and the turn-on time of the next scanning line is avoided, and the display device can be ensured to normally display pictures.
2. The power switching control circuit of claim 1, wherein the regulated switching circuit comprises a first resistor, a second resistor, a first transistor, a diode, a first capacitor, and a regulation module;
a first end of the first resistor is connected with the control signal input end, and a second end of the first resistor is connected with a first end of the second resistor, a first end of the first capacitor and a controlled end of the first transistor; a second end of the second resistor, a second end of the first capacitor and a second connecting end of the first transistor are grounded;
the first connection end of the first transistor is connected with the cathode of the diode through the voltage stabilizing module, and the anode of the diode is connected with the controlled end of the power switch circuit.
3. The power switching control circuit of claim 2, wherein the voltage regulator module comprises a first voltage regulator diode, a second voltage regulator diode, and a third voltage regulator diode;
the anode of the first voltage stabilizing diode is connected with the first connecting end of the first transistor, and the cathode of the first voltage stabilizing diode is connected with the anode of the second voltage stabilizing diode; and the cathode of the second voltage-stabilizing diode is connected with the anode of the third voltage-stabilizing diode, and the cathode of the third voltage-stabilizing diode is connected with the controlled end of the power switch circuit.
4. The power switching control circuit of claim 3 wherein said first transistor is an N-MOS transistor;
the grid electrode of the N-MOS tube is the controlled end of the first transistor, the drain electrode of the N-MOS tube is the first connecting end of the first transistor, and the source electrode of the N-MOS tube is the second connecting end of the first transistor.
5. The power switching control circuit of claim 2, wherein the current amplification circuit comprises a fifth resistor and an NPN triode;
a first end of the fifth resistor is connected with the voltage input end, and a second end of the fifth resistor is connected with a base electrode of the NPN triode and a negative electrode of the diode;
and the collector of the NPN triode is connected with the voltage input end, and the emitter of the NPN triode is connected with the controlled end of the power switching circuit.
6. The power switching control circuit of claim 1, wherein the power switching circuit comprises a third resistor, a fourth resistor, and a second transistor;
the first end of the third resistor is a controlled end of the power switch circuit, and the second end of the third resistor is connected with the first end of the fourth resistor and the controlled end of the second transistor;
the first connecting end of the second transistor is the input end of the power switch circuit and is connected with the second end of the fourth resistor; and the second connecting end of the second transistor is the output end of the power switch circuit.
7. The power switching control circuit of claim 6, wherein the second transistor is a P-MOS transistor;
the grid electrode of the P-MOS transistor is the controlled end of the second transistor, the source electrode of the P-MOS transistor is the first connecting end of the second transistor, and the drain electrode of the P-MOS transistor is the second connecting end of the second transistor.
8. The power supply switching control circuit according to any one of claims 1 to 7, wherein the power supply switching control circuit further comprises a discharge circuit;
the input end of the discharge circuit is connected with the voltage output end, and the output end of the discharge circuit is grounded.
9. The power switching control circuit of claim 8, wherein the discharge circuit comprises a second capacitor, a sixth resistor, a seventh resistor, an eighth resistor, and a ninth resistor;
the first end of the second capacitor, the first end of the sixth resistor, the first end of the seventh resistor, the first end of the eighth resistor and the first end of the ninth resistor are all connected with the voltage output end; the second end of the second capacitor, the second end of the sixth resistor, the second end of the seventh resistor, the second end of the eighth resistor and the second end of the ninth resistor are all grounded.
10. A display device characterized in that the display device comprises the power supply switching control circuit according to any one of claims 1 to 9.
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| CN202010371301.0A CN111564144B (en) | 2020-04-30 | 2020-04-30 | Power supply switching control circuit and display device |
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| CN202010371301.0A CN111564144B (en) | 2020-04-30 | 2020-04-30 | Power supply switching control circuit and display device |
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| CN111564144B true CN111564144B (en) | 2021-09-03 |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102594326A (en) * | 2012-01-16 | 2012-07-18 | 惠州三华工业有限公司 | Voltage stabilizing switching circuit for power supply |
| CN202797938U (en) * | 2012-08-10 | 2013-03-13 | 深圳创维－Rgb电子有限公司 | Overvoltage protection circuit and TV set |
| CN209267542U (en) * | 2018-12-29 | 2019-08-16 | 深圳Tcl新技术有限公司 | Slop control switching circuit and electronic equipment |
| CN111508441A (en) * | 2020-04-23 | 2020-08-07 | 深圳创维－Rgb电子有限公司 | Mini-L ED backlight source control system and television |
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2020
- 2020-04-30 CN CN202010371301.0A patent/CN111564144B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102594326A (en) * | 2012-01-16 | 2012-07-18 | 惠州三华工业有限公司 | Voltage stabilizing switching circuit for power supply |
| CN202797938U (en) * | 2012-08-10 | 2013-03-13 | 深圳创维－Rgb电子有限公司 | Overvoltage protection circuit and TV set |
| CN209267542U (en) * | 2018-12-29 | 2019-08-16 | 深圳Tcl新技术有限公司 | Slop control switching circuit and electronic equipment |
| CN111508441A (en) * | 2020-04-23 | 2020-08-07 | 深圳创维－Rgb电子有限公司 | Mini-L ED backlight source control system and television |
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